Vacuum pump

ABSTRACT

A vacuum pump ( 10 ) has a pump rotor ( 14 ) and a pump stator ( 12 ). The pump rotor ( 14 ) has an electrical measuring transducer ( 44 ), for example a temperature sensor. A transmitting antenna ( 40 ), which is connected with the measuring transducer ( 44 ), is provided on the pump rotor ( 14 ). A receiving antenna ( 30 ), which receives measurement values of the measuring transducer ( 44 ) from the transmitting antenna ( 40 ), is provided on the pump stator ( 12 ) so as to be situated opposite the transmitting antenna ( 40 ). In this way, accurate measurement values can be transmitted from the pump rotor ( 14 ) to the pump stator ( 12 ).

The invention refers to a vacuum pump comprising a pump rotor and a pump stator.

With vacuum pumps, and especially with fast rotating turbomolecular pumps, the pump rotor may be heated up a lot by compression heat, friction heat and possibly other influences. Excessive rotor temperatures increase the risk of crashes, foster material fatigue and change other characteristics of the pump rotor. For this reason it is necessary to monitor the rotor temperature and to record it, if so desired.

The rotor temperature may be measured either by a comparatively costly pyrometric measurement. Alternatively, the rotor temperature can be determined indirectly, by measuring the stator temperature and by drawing conclusions therefrom as to the rotor temperature. The indirect measurement is not very precise and is not suitable for monitoring fast temperature changes of the pump rotor.

In view of this, it is an object of the invention to provide a vacuum pump, wherein physical measurands of the pump rotor can be detected economically and precisely.

This object is achieved, according to the invention, with the features of claim 1.

According to the invention, the pump rotor comprises an electric measuring transducer and a transmitting antenna connected to the measuring transducer. A receiving antenna is provided at the pump stator, which receives measured values of the measuring transducer from the measuring antenna that transmits measured values measured by the measuring transducer. In this manner, a wireless radio connection for transmitting measured values between the pump rotor and the pump stator is established. Thus, an expensive pyrometric measurement or inaccurate indirect measurements of variable physical parameters of the pump rotor can be dispensed with. Since the measuring transducer is located immediately at the pump rotor, the respective parameter can be detected very precisely. The measured value is transmitted from the transmitting antenna to the receiving antenna either analogously or digitally, whereby a safe, fast, exact and error-free transmission can be guaranteed.

Preferably, the measuring transducer is a temperature sensor, but it may also be an acceleration or a vibration sensor or a strain sensor or a combination of a plurality of the sensors mentioned.

In a preferred embodiment, both the pump stator and the pump rotor are provided with a respective energy transmission coil, the coil on the side of the pump rotor being connected with the measuring transducer through a voltage transformer, so that electric energy can be transmitted wirelessly from the pump stator to the pump rotor for the supply of electric energy to the measuring transducer. Both energy transmission coils form the primary circuit and the secondary circuit of a transformer. By supplying a corresponding alternating voltage into the energy transmission coil on the side of the pump stator, the same is transferred to the energy transmission coil on the side of the pump rotor, so that electric energy is available in the pump rotor to supply the measuring transducer and possibly other aggregates.

The two energy transmission coils may also be part of the drive motor, i.e. they may be formed by a portion of a stator coil on the side of an engine stator and a rotor coil on the side of an engine rotor. The transmitting antenna and the receiving antenna may also serve as energy transmission coils.

The transmitting antenna and the receiving antenna may be arranged axially or radially with respect to each other. The transmission antenna and the receiving antenna may be arranged in the vicinity of the axial plane of the pump rotor. However, the transmission antenna and the receiving antenna may also be arranged outside and remote from the axial plane of the pump rotor. Preferably, one of the antennas is annular in shape. This is necessary, if both antennas are situated around a rotor shaft. In order to guarantee sufficiently long transmission times, especially at high speeds of rotation of more than 10000 rotations per minute, both antennas overlap for the major part or the entire circumference. This allows for a relatively long or possibly a continuous transmission of measured values between the transmitting antenna and the receiving antenna. If both antennas are annular in shape, but discontinuous, they may each at the same time be used as a primary and a secondary coil for energy transmission.

In a preferred embodiment, a transponder is arranged at the pump rotor, which sends a measured value from the measuring transducer via the trans-mission antenna to the receiving antenna only upon request. In this manner, a corresponding stator-side control can adjust the measuring value transmission interval to the respective situation. Thus, the number of transmissions of measured values is kept as low as possible, whereby the electric energy requirement of the rotor is kept as low as possible. Thereby, in turn, the aggregates concerned with the energy supply to the rotor can be designed as small as possible.

An embodiment of the invention is detailed hereinafter with reference to the drawing.

The FIGURE is a schematic illustration of a vacuum pump.

The FIGURE represents a vacuum pump 10 designed as a turbomolecular pump. The vacuum pump 10 has a pump part substantially formed by a pump stator 12 and a pump rotor 14. Further, the vacuum pump has a drive and bearing part, wherein two shaft bearings 16, 18 and a drive motor 20 are arranged.

On the side of the stator, a receiving antenna 30 is provided that is configured open and is arranged annularly about the rotor shaft 22. The stator-side receiver antenna 30 is electrically connected to a control module 32 that serves to control the transmission and receiving operation and the evaluation of the signals received by the receiver antenna 30.

On the side of the rotor, and exactly axially opposite thereto, a corresponding annular transmitting antenna 40 is provided. Further, the pump rotor 14 comprises a temperature sensor connected to a transponder 42 which in turn is connected to the transmitting antenna 40.

The measuring transducer 44 is a temperature sensor measuring the rotor temperature and transmitting this value to the transponder 42 either continuously or on demand. As an alternative or in addition, the measuring transducers used could also be strain sensors, acceleration sensors or vibration sensors or other sensors.

The receiving antenna 30 is also configured as an open annulus and also serves, besides its function as an antenna, as a secondary coil of a transformer, for which the receiving antenna 30 forms the primary coil. The control device 32 feeds a corresponding alternating voltage into the receiving antenna 30 that is induced into the transmitting antenna 40. The axial distance between the receiving antenna 30 and the transmitting antenna 40 is a few millimetres and possibly even less than 1 mm.

The transponder 42 in the pump rotor 14 has a transceiver unit receiving request signals from the control module 32, amplifies and interprets these, and, upon a request, passes appropriately amplified measured values from the measuring transducer 44 to the transmission antenna 40.

In the pump rotor 14, a voltage transformer 46 is provided that rectifies the alternating voltage received, controls the same to a constant supply voltage and feeds electric energy to the measuring transducer 44 and the transponder 42 via supply lines.

The wireless radio transmission of measured values provided by measuring transducers on the side of the pump rotor, allows for a comprehensive, exact and real-time monitoring of the pump rotor. Thus, upon an imminent risk of a crash due to an overheating of the rotor, quick action can be taken by a motor control and a damage to or destruction of the vacuum pump can be avoided. Further, it is possible, especially by monitoring and recording the pump rotor temperature, to track and extrapolate the ageing of the pump rotor or to significantly extend the useful life of the vacuum pump by avoiding high pump rotor temperatures. 

1. A vacuum pump comprising a pump rotor; a pump stator; the pump rotor including an electric measuring transducer, a transmitting antenna at the pump rotor, which transmitting antenna is connected to the measuring transducer; and a receiving antenna at the pump stator, which receiving antenna receives measured values measured by the measuring transducer from the transmitting antenna.
 2. The vacuum pump of claim 1, wherein a respective energy transmission coil is provided at the pump stator and the pump rotor, the energy transmission coil on the side of the pump rotor providing electric energy for the measuring transducer the electric energy being transmitted wirelessly from the pump stator to the pump rotor to supply electric energy to the measuring transducer.
 3. The vacuum pump of claim 1, wherein at least one of the transmitting and receiving antennas is annular in shape.
 4. The vacuum pump of claim 1, further including: a transponder at the pump rotor, which transponder is connected to the measuring transducer and the transmitting antenna, and which transponder, upon a request, causes a transmission of a measured value from the measuring transducer via the transmitting antenna.
 5. The vacuum pump of claim 1, wherein the measuring transducer is a temperature sensor.
 6. The vacuum pump of claim 1, wherein the vacuum pump is a turbomolecular pump.
 7. A turbomolecular vacuum pump comprising: a stator; a rotor rotatably mounted in the stator; a sensor mounted on the rotor to measure a characteristic of the rotor; a rotor side coil mounted on the rotor for rotation therewith and connected with the sensor; a stator side coil mounted on the stator adjacent the rotor side coil, the stator and rotor side coils electrically coupling to communication at least one of electric energy and electrical signals indicative of the measured rotor characteristic therebetween; a motor mounted at least partially to the stator to rotate the rotor relative to the stator; and, a control module connected with the stator coil to evaluate the electrical signals.
 8. The vacuum pump of claim 7, wherein the control module is connected with the motor to control the motor in accordance with the measured rotor characteristic.
 9. The vacuum pump of claim 7, wherein the sensor includes at least one of a temperature sensor, a strain sensor, an acceleration sensor, and a vibration sensor.
 10. The vacuum pump of claim 7, further including: a transponder mounted on the rotor and connected with the rotor coil and the senstor to control and power the sensor and to communicate the electrical signals indicative of the measured rotor characteristic to the rotor coil. 